Flow field analysis and structural optimization of coating die with electrode slurry

doi:10.19799/j.cnki.2095-4239.2024.0100

Abstract

Abstract:

The coating process is one of the key processes in the manufacturing of lithium battery electrodes. The stability and consistency of the coating determine the structure of the electrode, which in turn affects the performance and cycle life of the battery. As large-sized power lithium battery products had higher requirements for coating width, one of the core technical issues is how to ensure the flow uniformity of electrode slurry at the outlet of the coating die. Therefore, rational design of the flow channel structure of the coating die is crucial. This study aims to address the issue of inhomogeneous velocity distribution at the outlet of the wide coating die, and constructs die head flow channel models with different sizes and structures for flow field simulation. The flow characteristics of electrode slurry inside the die head are analyzed, and the structural dimensions of the coat-hanger die are optimized by using Box-Behnken design. The coat-hanger die with an inclined variable-diameter homogenizing cavity had a stronger drainage effect on the slurry, helping to improve the flow uniformity in the width direction. Adjustments to the die structure dimensions significantly impacted flow uniformity. The main structural parameters of the coat-hanger die were optimized using Box-Behnken design, resulting in an increase in the uniformity of the slurry to 0.99.

Key words: lithium-ion batteries, slot-die coating, coat-hanger die, computational fluid dynamics, Box-Behnken design

CLC Number:

TQ 024.1

Jiamu YANG, Yuxin CHEN, Cheng LIAN, Zhi XU, Honglai LIU. Flow field analysis and structural optimization of coating die with electrode slurry[J]. Energy Storage Science and Technology, 2024, 13(4): 1109-1117.

Figures/Tables 12

Fig. 1

Fig. 2

Table 1

Structural parameters of model and properties parameters of slurry"

参数	数值	单位
模头宽度，W	600, 800, 1000, 1200, 1400	mm
狭缝厚度，h	1	mm
模头高度，l	100	mm
进料管半径，r_l	5	mm
匀料腔半径，R	10	mm
二级匀料腔半径，r	4	mm
进料管长，L	80	mm
浆料密度，ρ	1320	kg/m³
浆料表面张力，σ	0.066	N/m
浆料黏度，μ	$M γ γ r e f N - 1$	Pa∙s
参考剪切速率，γ_ref	1	s^-1
流体一致性系数，M	3.585	Pa∙s
流动特性指数，N	0.6322	—
倾斜角，θ	0, 2.5, 5, 7.5, 10	(°)
衣架式匀料腔中心半径，R_h	10	mm
衣架式匀料腔端部半径，r_h	10, 7.5, 5, 2.5, 1	mm
扇形区高度，H	$W t a n θ$	mm
松弛区高度，y	40, 60, 80, 100, 120	mm

Table 1

Fig. 3

Fig. 4

Fig. 5

Fig. 6

Fig. 7

Fig. 8

Fig. 9

Table 2

Scheme parameter values of Box-Behnken design"

序号	因素x₁：倾斜角	因素x₂：匀料腔端部半径	因素x₃：松弛区高度	均匀度 $U v$
1	0	0	0	0.91
2	1	0	1	0.956
3	-1	0	-1	0.805
4	1	0	-1	0.932
5	-1	0	1	0.875
6	0	0	0	0.91
7	0	-1	-1	0.748
8	0	1	1	0.982
9	0	1	-1	0.978
10	0	-1	1	0.823
11	-1	1	0	0.921
12	0	0	0	0.91
13	1	-1	0	0.861
14	0	0	0	0.91
15	-1	-1	0	0.748
16	1	1	0	0.874
17	0	0	0	0.91

Table 2

Fig. 10

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